Carousel bottling and packaging systems of conventional design comprise a bed presenting a plurality of bays serving to accommodate respective carousel machine units on which containers are processed, and in particular sterilized, filled with a selected product, then closed with a cap. The bed also houses devices for transferring the containers from one carousel to the next, as well as infeed and outfeed devices by way of which the containers enter and exit the train of carousels.
In carousel type machines, containers filled with a given product are transferred to a capping machine by which a cap or top is applied to the neck of the container, providing a closure.
In particular, carousel type capping machines comprise a revolving plate centred on a substantially vertical axis of rotation and carrying a plurality of peripheral pedestals on which to stand the containers. The containers are directed onto the plate at an infeed station, and released from the plate at an outfeed station separated by a given angular distance from the infeed station. Each container is closed with a cap as it advances, generally along a circular path, between the infeed station and the outfeed station.
For this purpose, capping machines are equipped with a plurality of capping units, each incorporating a relative capping head, positioned vertically above the plurality of pedestals accommodating the containers and revolving about the same axis of rotation as the plate.
In particular, during the rotation of the plate, each capping unit advances while remaining vertically aligned above a container standing on a respective pedestal, and descends simultaneously to the point at which the capping head makes contact with the neck of the container. At this point, a cap or top, offered loosely at first to the neck of the container, will be secured by the capping head. The cap can be screwed or snapped onto the neck, or fitted by a combination of both these actions, depending on the style of cap.
To ensure that the capping units can rotate together with the containers occupying the pedestals, the units are arranged radially about a vertical shaft to which the plate presenting the pedestals is also keyed, so that the single pedestals are arranged likewise radially about the shaft.
The position of the capping units is locked angularly (though not axially) to that of the vertical shaft, so that when the shaft is set in rotation, both the capping units uppermost and the pedestals below will revolve permanently in vertical alignment one with another.
Also, in order that the capping units can be lowered onto the respective containers during the rotation of the carousel, each unit is furnished with one or more following members engaging in a channel that functions as the active profile of a cylindrical cam. The cam is located concentrically between the rotating vertical shaft and the capping units arranged radially about the shaft. The cylindrical cam does not rotate but remains stationary, in other words permanently occupying the same position, whatever the angular position of the vertical shaft and the capping units.
Consequently, as the capping units revolve around the cylindrical cam, they can also be displaced in a vertical direction by the interaction of the following members with the cam profile.
In capping machines typical of the prior art, to guarantee that the cylindrical cam located between the rotating vertical shaft and the capping units will not rotate but remain stationary, the structure includes two vertical columns anchored to the floor and rising parallel to the vertical shaft. The cylindrical cam is made fast to the two columns, so that the columns serve in practice both to support and to keep the cam in a predetermined position as the capping carousel rotates.
Moreover, given that these capping machines must be able to handle different types or styles of containers, depending on the product being packaged any one time (mineral oils, milk, fruit juices, washing powders), the operating distance between the capping units and the pedestals on which the containers are placed must be adjustable in order to suit the height of the container currently in use.
To this end, the capping units are mounted slidably to the rotating vertical shaft, and the cylindrical cam controlling the vertical movement of each capping unit toward and away from the neck of the relative container is mounted slidably to the fixed columns.
In particular, the capping units are raised and lowered relative to the vertical shaft by means of a lead screw coupled to a lead nut anchored rotatably to the capping units (and therefore to the rotating vertical shaft). The lead screw is driven by an electric motor and housed internally of the rotating vertical shaft. To ensure that the lead nut, driven in rotation by the vertical shaft, cannot turn on the lead screw during the operation of the capping machine (causing the capping units to be raised or lowered, with adverse consequences), the lead screw is coupled to the electric motor by way of a pneumatic clutch and thus freewheelable, with the result that the entire lead nut and lead screw assembly can rotate as one with the vertical shaft, free of any other constraint, as long as the capping machine is in operation.
The cylindrical cam is coupled to the columns by way of upright members rigidly associated with the cam and slidably associated, by way of sleeves, with the columns.
Thus, the entire superstructure consisting of the capping units and the cylindrical cam can be moved toward or away from the revolving plate.
Capping machines of the prior art described briefly above are affected by certain drawbacks.
Firstly, such machines are particularly expensive, given that the vertical columns supporting the cylindrical cam must necessarily be made of structural steel and encased in stainless steel machine-turned to exact design tolerances in order to guarantee a faultless coupling between the selfsame columns and the aforementioned sleeves, avoiding any clearances that could induce even minimal oscillations of the cylindrical cam and jeopardize the smooth operation of the machine.
Conversely, if there is zero clearance in the fit between the sleeves and the columns, the sleeves will bind when sliding on the columns during the operation of adjusting the vertical distance between the capping units and the pedestals.
Moreover, the use of particularly high cost materials (stainless steel) for the construction of the columns is dictated by the need for thorough sanitization of these same columns when switching from one kind of process to another (from bottling lubricating oils to bottling milk, by way of example).
Similarly, the inclusion of the pneumatic clutch not only increases the costs of construction but also seriously complicates the design of the machine as a whole. Also, in the event that the clutch should fail to uncouple the lead screw completely from the electric motor, the operation of the capping machine will need to be suspended at frequent intervals in order to adjust the height of the capping units above the pedestals.
Moreover, with the inclusion of the vertical columns supporting the cylindrical cam, the integration of the capping machine into a train with other carousels is rendered especially problematical.